There has conventionally been known a refrigerating system comprising a plurality of refrigerant circuits such as one disclosed in Japanese Unexamined Patent Publication No. SHO 62-238951. The refrigerating system of this type comprises a primary refrigerant circuit composed of: a compressor; a heat-source-side heat exchanger; a pressure reducing mechanism;
and a heat-source-side heat exchanging part of a middle heat exchanger which are connected to each other by refrigerant piping and a secondary refrigerant circuit composed of a pump, a use-side heat exchanging part of the middle heat exchanger, and a use-side heat exchanger which are connected to each other by the refrigerant piping. In the middle heat exchanger, heat is exchangeable between the heat-source-side heat exchanging part and the use-side heat exchanging part. In the case of applying the system to an air conditioner, the use-side heat exchanger is disposed in a room.
In such a structure, indoor air conditioning is performed by causing a heat exchange between the primary refrigerant circuit and the secondary refrigerant circuit by means of the middle heat exchanger and transferring heat from the primary refrigerant circuit to the secondary refrigerant circuit.
As an example of a refrigerating system having a plurality of use-side heat exchangers each capable of selectively performing heat absorbing operation and heat releasing operation, there is an apparatus disclosed in Japanese Unexamined Patent Publication No. HEI 6-82110. The primary refrigerant circuit of the apparatus has a primary heat exchanger for heating and a primary heat exchanger for cooling. On the other hand, the secondary refrigerant circuit thereof has a circuit for heating and a circuit for cooling. In the circuit for heating, a secondary heat exchanger for heating which exchanges heat with the primary heat exchanger for heating, an indoor heat exchanger for heating, and a pump are connected successively. In the circuit for cooling, a secondary heat exchanger for cooling which exchanges heat with the primary heat exchanger for cooling, an indoor heat exchanger for cooling, and a pump are connected successively.
In the structure, if a cooling load is larger than a heating load, the heat-source-side heat exchanger of the primary refrigerant circuit is used as a condenser. Conversely, if the heating load is larger than the cooling load, the heat-source-side heat exchanger of the primary refrigerant circuit is used as an evaporator. This enables some of the use-side heat exchangers and the others thereof to simultaneously and individually perform heat absorbing operation and heat releasing operation in accordance with an air conditioning load.
Problems to be Solved by the Invention
The primary refrigerant circuit, the secondary heat exchanger for heating, and the secondary heat exchanger for cooling are contained in an outdoor unit of the foregoing apparatus in which the plurality of use-side heat exchangers are capable of simultaneously and individually performing the heat absorbing operation and the heat releasing operation. On the other hand, the indoor heat exchanger for heating and the indoor heat exchanger for cooling are contained in each of indoor units. The outdoor unit and the indoor unit are connected to each other by four connecting pipes. Specifically, the outdoor unit and the indoor unit are connected to each other by outgoing and incoming pipes for the heating circuit and outgoing and incoming pipes for the cooling circuit.
In the apparatus of this type, there has been a request for a reduction in the number of connecting pipes in order to provide a simpler structure and a simpler installing operation. However, since each of the heating circuit and the cooling circuit requires the outgoing pipe and the incoming pipe in the foregoing structure, the requirement cannot be satisfied.
The present invention has been achieved in view of the foregoing and it is therefore an object of the present invention to provide a secondary refrigerant system comprising a plurality of use-side heat exchangers, which is a refrigerating apparatus wherein the heat exchangers are capable of simultaneously and individually performing heat absorbing operation and heat releasing operation and a reduced number of connecting pipes are provided.